Exxon Mobil Corp. (XOM) is gaining 0.64 percent to $90.55. The company's fourth quarter profit improved from the same period a year earlier and was above Wall Street view. Quarterly total revenues and other income rose from the year-ago quarter, but missed the consensus estimate.

Dell Inc. (DELL) is rising more than 5 percent to $13.99 amidst reports on buyout plans.

Perrigo Co. (PRGO) is rising over 4 percent to $105.00. The company's second quarter earnings and net sales improved from the year-ago quarter and were above Wall Street view. Perrigo also announced it has agreed to acquire companion animal health company Velcera, Inc. (VLCR.OB) for $160 million in cash.

Tidewater Inc. (TDW) is up more than 4 percent to $51.39. The company's third quarter earnings declined from the previous year period, but were above Wall Street view. Revenues also topped the consensus estimate.

VIVUS Inc. (VVUS) is up over 5 percent to $12.77. The company announced the publication of a study concluding that weight loss with Qsymia significantly improves multiple cardiovascular disease risk factors.

Decliners:

Merck & Co. Inc. (MRK) is down nearly 3 percent to $42.05. The company's fourth quarter earnings declined from the prior year period, but its non-GAAP earnings per share were above analysts' estimate. Sales fell 5 percent, but topped the consensus estimate. The company expects full-year 2013 non-GAAP earnings per share in-line with analysts' expectation.

Mattel, Inc. (MAT) is falling 2 percent to $36.75. The company's fourth quarter profit declined from the year-ago quarter and its adjusted earnings per share were below Wall Street view. Worldwide net sales for the quarter rose 5 percent, but missed the consensus estimate by a marginal amount.

Legg Mason, Inc. (LM) is sliding 2 percent to $36.75. The company slipped to a loss in its third quarter due to non-cash impairment charges related to intangible assets. Operating revenues rose 7 percent, but were below analysts' projection.